This invention relates to web heating and pressing apparatus, more particularly to such apparatus comprising a heated roll and a backing or anvil roll between which superimposed webs are fed for pressurized heat-transfer contact of the heated roll with one of the webs, and specifically to such apparatus for use in the application of foil areas and the embossing of the foil areas for the production of holographic images on a substrate web such as a paper web.
Reference is made to U.S. Pat. No. 5,464,690, issued Nov. 7, 1995, entitled Holographic Document and Method for Forming, hereinafter referred to as the ""690 patent, and incorporated herein by reference, showing in FIG. 6 thereof a document having a security holographic image thereon to prevent counterfeiting, reference being made in column 4, lines 1-3 of this patent to the document being a stock certificate or check, or any other desired document upon which it is desired to have embossed a diffraction grating image or a hologram. The document is described in the ""690 patent as comprising a substrate of plain or printed paper, coated paper or plastic film (the xe2x80x9cdocument substratexe2x80x9d) having a xe2x80x9cchipxe2x80x9d bearing the holograph image identified by the reference numeral 16.
As illustrated in FIG. 4 of the ""690 patent, a continuous web 20 (the xe2x80x9cdocument substratexe2x80x9d), which is ultimately segmented into individual sheets constituting the documents, is intermittently fed forward through a stamping station wherein a composite sheet or web 10 of the so-called xe2x80x9cx-factorxe2x80x9d construction including foil layer C is intermittently fed over web 20 transversely thereof and, during dwell intervals, a hot stamping head 26 carrying a die 28 is driven down to press down on the composite sheet 10 causing a portion of the composite strip constituting the xe2x80x9cchipxe2x80x9d 101 to adhere to the web 20. The chip 101, adhering to the web 20, separates from the composite sheet, and the web 20 with chips 101 adhered thereto feeds forward through an embossing station where each chip (having the foil layer C) is embossed to produce the hologram image thereon. FIG. 5 of the ""690 patent shows an alternative procedure wherein the web 20 is continuously fed forward with the composite sheet or web 10 superimposed on the web 20 and extending in the same direction as the web 20, the composite sheet or web 10 having heat and pressure applied thereto to punch out chips 101 from the composite sheet and cause them to adhere to the web, each chip having the foil layer C which is subsequently embossed to produce the holographic image thereon.
This invention involves apparatus for use in an installation for continuous feed therethrough of the paper or film substrate, which may be referred to as the base web, with the chip-forming web (which may be referred to as the foil web) thereon for carrying out the stamping operation at the stamping station to stamp or punch out the chips and cause them to adhere to the base web, ahead of the embossing station, and apparatus for use in the installation at the embossing station for embossing the chips. In respect to the function of the stamping apparatus to apply heat and pressure in the limited area of the foil web, and the function of the embossing apparatus to apply heat and pressure in the limited area of each chip, apparatus of this invention is herewith broadly entitled xe2x80x9cWeb Heating and Pressing Apparatusxe2x80x9d, noting also that it is contemplated that the principles of the apparatus may be applicable to apparatus other than the herein-disclosed apparatus for stamping the foil web superimposed on the substrate or the base web and the apparatus for embossing the chips.
Reference is also made to U.S. Pat. No. 5,618,378 issued Apr. 8, 1997, entitled Apparatus for Applying Images, Particularly Security Images to Banknotes, hereinafter referred to as the ""378 patent, and incorporated herein by reference, involving apparatus for applying a series of images (holographic security images) to moving stock (material in sheet or web form), especially for its disclosure of what may be termed xe2x80x9cincremental feedxe2x80x9d of the images, i.e. feed of closely spaced images onto the moving stock at intervals greater than the spacing of the images. This ""378 reference is incorporated herein by reference since the above-described installation in which stamping apparatus of the present invention may be used may utilize the xe2x80x9cincremental feedxe2x80x9d principle thereof for feeding the foil web to said stamping apparatus.
Reference is made further to the co-assigned U.S. Pat. No. 5,058,496 issued Oct. 22, 1991, entitled Roll Apparatus with Cooling System for Maintaining Constant Gap Size and Method, hereinafter referred to as the ""496 patent, showing a die cutter comprising a pair of rolls each having trunnions at its ends journalled for rotation in bearings in the frame with a cooling system for the bearings wherein a coolant is pumped through the bearings and the temperature of the coolant is controlled by a temperature sensor associated with the frame. This ""496 patent is incorporated herein by reference since the present invention may utilize a similar coolant temperature control system.
Reference is also made to U.S. Pat. No. 4,519,757 issued May 28, 1985, entitled Web Surface Treating Apparatus, hereinafter referred to as the ""757 patent, showing apparatus including heated rolls 5, 7 and 9 each constructed for circulation of heated liquid therethrough. This ""757 patent is incorporated herein by reference since the present invention may utilize similar heated rolls.
Among the several objects of the invention may be noted the provision of web heating and pressing apparatus comprising a heated roll and an anvil roll between which web material is fed for application of heat and pressure thereto, said rolls having trunnions journalled in bearings, with a cooling system for cooling the bearings of both rolls and the trunnions of the heated roll to reduce transfer of heat to the frame for dimensional stability of the frame; the provision of such apparatus, more particularly stamping apparatus for the application of foil areas (xe2x80x9cchipsxe2x80x9d) on a substrate web, such as a web of paper or film web for the production of holographic images thereon; the provision of such apparatus, more particularly embossing apparatus, for embossing each chip with a holographic image; and the provision of such apparatus capable of relatively high speed operation in the production of the substrate web with the chips for subsequent embossing of the chips and the embossing of the chips, needing adjustment relatively infrequently.
In general, web heating and pressing apparatus of this invention comprises a frame, a heated roll and an anvil roll each having trunnions at its ends journalled for rotation in bearings in the frame with the axes of the rolls at least substantially parallel and with the rolls so mounted as to provide a web pass plane between the rolls, and a cooling system for cooling the bearings for the trunnions of the heated roll, for cooling the bearings for the trunnions of the anvil roll and for cooling the trunnions of the heated roll. The cooling system comprises passaging for flow of coolant in heat-transfer relation with the bearings for the trunnions of the heated roll, passaging for flow of coolant in heat-transfer relation with the bearings for the trunnions of the anvil roll, and a cooling chamber for flow of coolant therethrough in heat-transfer relation to the trunnions of the heated roll, said passaging and cooling chamber being connected in a circuit for circulation of coolant therethrough for cooling the bearings for the trunnions of both rolls and the trunnions of the heated roll.
Other objects and features will be in part apparent and in part pointed out hereinafter.